add method

src/qibojit/backends/gpu.py

@@ -1,4 +1,7 @@
+from typing import Union
+
 import numpy as np
+
 from qibo.backends.numpy import NumpyBackend
 from qibo.config import log, raise_error
 
@@ -503,7 +506,7 @@ def calculate_matrix_exp(self, a, matrix, eigenvectors=None, eigenvalues=None):
             if self.is_sparse(matrix):
                 from scipy.sparse.linalg import expm
 
-                return self.cast(expm(-1j * a * matrix.get()))
+                return self.cast(expm(-1j * a * self.to_numpy(matrix)))
             else:
                 from cupyx.scipy.linalg import expm  # pylint: disable=import-error
 
@@ -513,6 +516,15 @@ def calculate_matrix_exp(self, a, matrix, eigenvectors=None, eigenvalues=None):
             ud = self.cp.transpose(self.cp.conj(eigenvectors))
             return self.cp.matmul(eigenvectors, self.cp.matmul(expd, ud))
 
+    def calculate_matrix_power(self, matrix, power: Union[float, int]):
+        if isinstance(power, int):
+            return self.cp.linalg.matrix_power(matrix, power)
+
+        copied = self.to_numpy(matrix)
+        copied = super().calculate_matrix_power(copied, power)
+
+        return self.cast(copied, dtype=copied.dtype)
+
 
 class CuQuantumBackend(CupyBackend):  # pragma: no cover
     # CI does not test for GPU